Online mixing courses & recording lessons, etc.

What you should do is get onto a local studio and ask them if you could assist for a few sessions to get experience.
No amount of videos will be as good as actually being there in the thick of a real commercial session.

i´m totally with you,that would be the ideal case.. but thats easier said than done.
From my personal (frustrating) experience this is not possible or doesnt work out so easily.. unfortunatly :(
You may even find out its a pure waste of time because the studio is not up to your quality standards or you have no chemistry with them.
And lots of engineers and producers with great knowledge and experience to share, often have no time and nerves for someone (pronably from a strange guy they never heard before) to lurk around and "assist" at their studio on already thight production schedules and even have lesser time to tell you their philosphy behind it, why they did this and that.. you may be able to just look what they do ,but dont have a clue why they do it.
it might be easier if you already got lots of contacts in the studio scene and are friends with some of those people, but if you arnt. its not so easy

so having the option to learn from well made online course is indeed a great opportunty to gain knowledge and inspiration.

Because at the end you only get better by doing it by yourself and made your experiences
 
What you should do is get onto a local studio and ask them if you could assist for a few sessions to get experience.
No amount of videos will be as good as actually being there in the thick of a real commercial session.

Yes of course but around my place there is no 'real' studios and even less Metal studios. I did spend a few days in a famous studios in Denmark a few years ago and yes, it actually gave me many great tips and stuff but what I need, I guess is to learn listening if that makes sense. The few videos I saw were good to listen to raw tracks, mixed tracks and soloed tracks. And so far, it learnt me a lot as I used to misinterpreted what I was hearing. Dunno if I'm clear tho :D